The present invention relates to absorbent articles such as diapers, training pants, adult incontinence articles, bed mats, and the like. In particular, the present invention relates to those absorbent articles which store urine by means of either capillary or osmotic pressure.
Absorbent articles such as diapers, training pants, adult incontinence articles, bed mats, and the like are well known in the art and are frequently used for example for babies, toddlers, incontinent persons, and bed-ridden persons.
It has been recognized in the prior art that storing acquired urine close to the respective body exit may bear inherent disadvantages. The human urethra is located almost in between the legs of the human being. Hence, storage in particular of larger gushes of urine close to the urethra would lead to increased bulk in between the legs of the wearer. Increased bulk, of course, limits the mobility of the wearer and thus is uncomfortable. It is therefore desirable to store the acquired urine away from the point of acquisition.
To minimize the caliper over the entire storage area and to optimize material usage within that storage region, it is further desired to distribute the liquid as easily as possible over the storage area.
PCT patent publication WO 98/22067 (Matthews et al.) provides a personal care product in which the ratio of the amount of liquid stored in the center region to the amount of liquid storage in at least one of the end regions 30 minutes after an insult is less than 5:1. Whilst a small part of the acquired liquid is transported outside of the acquisition region, it has been failed to recognize how the acquired liquid should be distributed with in the storage region.
PCT patent application WO 98/43578 (LaVon et al.) provides an absorbent article comprising absorbent core with a crotch region and at least one waist region whereby said crotch region has a lower ultimate liquid storage capability than the waist region. The article further has an improved liquid handling performance such as an acquisition rate of at least 0.6 ml/s in the fourth gush.
Hence, it is an object of the present invention to overcome the problems of the prior art absorbent articles.
It is a further object of the present invention to provide the absorbent article which transports acquired liquid out of the acquisition region and distribute the acquired liquid within the storage region.
It is a further object of the present invention to provide an absorbent article which stores the acquired liquid in a constant fill pattern outside the acquisition region.
The present invention provides absorbent article comprising an acquisition region, a first storage region being separate from said acquisition region, and a second storage region being separate from said acquisition region, said second storage region being symmetrically different from said first storage region. The article has a total design capacity, said first storage region having a capacity of at least 10% of said total design capacity, said second storage region having a capacity of at least 10% of said total design capacity. The absorbent article according to the present invention is characterized in that said article has a fill pattern difference of less than 30% according to the fill ratio test disclosed herein.
The present invention further provides a process for storing urine in an absorbent article. The article has an acquisition region, a first storage region being separate from said acquisition region, and a second storage region being separate from said acquisition region and being symmetrically different from said first storage region. The process for storing body fluids comprises the steps of:
acquiring liquid into said article at said acquisition region, the amount of liquid acquired into said acquisition region being a fraction A of the total design capacity of said article for managing urine,
storing liquid in a first liquid storage region, the amount of liquid being stored in said first liquid storage region being a fraction B1 of said acquired liquid, said fraction B1 being at least 10%,
storing liquid in a second liquid storage region, the amount of liquid being stored in said second liquid storage region being a fraction B2 of said acquired liquid, said fraction B2 being at least 10%.
The process of the present invention is characterized in that for any value of said fraction A between 20% and 80% the ratio of B1/B2 differs by less than 30% from the ratio of B1/B2 for a fraction A of 20%.
The present invention is described in the following by means of a variety of different embodiments and by means of a variety of different features. Further embodiments of the present invention may be obtained by combining features of one embodiment with features of another embodiment disclosed herein and/or with other features disclosed herein. These further embodiments are considered to be implicitly disclosed herein and hence form part of the present invention. It will be apparent to the skilled person that combinations of certain features may lead to non-functional articles not forming part of this present invention.
It is one aspect of the present invention to provide a process for storing urine in a article for managing urine in a constant storage pattern. It is another aspect of the present invention to provide a article for managing urine.
The absorbent article of the present invention is capable of storing urine in a constant pattern. In other words, the absorbent article of the present invention is capable of filling different storage regions with a constant filling ratio. For the purposes of the present invention, this capability is quantified by the Fill Ratio Test defined hereinafter. The absorbent article according to the present invention has a fill pattern difference of less than 30% according to the fill ratio test disclosed herein, preferably a fill ratio difference of less than 20%, more preferably a fill ratio difference of less than 10%, most preferably a fill ratio difference of less than 5%.
Preferably, the absorbent article of the present invention further rapidly acquires urine in an in-use configuration. For the purposes of the present invention, this capability is quantified by the curved acquisition test disclosed hereinafter. The absorbent article according to the present invention has a liquid acquisition rate in the fourth gush of at least 2 milliliters per second, preferably a liquid acquisition rate in the fourth gush of at least 2.5 milliliters per second, more preferably a liquid acquisition rate in the fourth gush of at least 3 milliliters per second, most preferably a liquid acquisition rate in the fourth gush of at least 4 milliliters per second.
The entire absorbent article of the present invention is intended to be worn by a wearer such that the wearer retains his mobility during use of the article of the present invention. In some embodiments of the present invention, the absorbent article of the present invention comprises an attachment means which is unitary with the article. The term xe2x80x9cunitaryxe2x80x9d as used herein indicates that the attachment means is joined to the absorbent article and that the attachment means is not intended to be separated from the article during use of the article. The attachment means is intended to hold the absorbent article of the present invention around the lower torso of the wearer during use. Suitable attachment means such as for example adhesive tapes, mechanical fasteners, garment like articles, and the like are well known in the art. Alternatively, the absorbent article of the present invention may be attached to the lower torso of the wearer by an attachment means which is not unitary with the article such as for example a pant.
It is further desirable for the absorbent article of the present invention that it is sufficiently flexible to readily conform with the body of the wearer during use.
For the purpose of the present invention, a Cartesian coordinate system is defined as follows. The zxe2x80x94direction is defined to be perpendicular to the surface of the acquisition region at the intended loading point. The xxe2x80x94direction is defined to coincide with the longitudinal dimension of the absorbent article. In the case of a diaper, the xxe2x80x94direction runs from the front region of the article (which comes into contact with the front waist region of the wearer during use) to the back region of the article (which comes into contact with the back waist region of the wearer during use). Accordingly, the yxe2x80x94direction coincides with a transverse dimension of the absorbent article which runs from the left to the right of the wearer during use. It is to be understood in this context that this Cartesian coordinate system is only a truly Cartesian coordinate system when the article is in the flat out configuration. For typical in use conditions, the configuration of the article is such that xxe2x80x94, yxe2x80x94, and zxe2x80x94direction as defined above only form a locally perpendicular set of coordinates.
The article of the present invention has a total design capacity. The term xe2x80x9ctotal design capacityxe2x80x9d as used herein refers to the maximum volume of body liquid that the article is designed to absorb. Typically, the total design capacity equals the combined capacity of all storage members under typical usage conditions. If the storage members can not be identified, then the total design capacity may be determined by the Capacity Dunk Test defined hereinafter. The total design capacity is also related to the amount of body liquid exudated by the user of the article during the intended usage period.
The article for managing body liquids of the present invention comprises at least one acquisition region. The term xe2x80x9cacquisition regionxe2x80x9d as used herein refers to that region of the article which comprises the intended loading point of the article. The term xe2x80x9cloading pointxe2x80x9d as used herein is that point or region of the article which is intended to be positioned closest to the exit of the urethra of the wearer during use. Typically, the acquisition region is dimensioned such that it allows for variation of the mutual relative positioning of the respective body exit with respect to the article. The acquisition region may also comprise means for intermediate storage of the acquired liquids. Generally, the acquisition region extends over at least a third of the longitudinal dimension of the absorbent article, extends over the entire transverse dimension of the absorbent article, and extends over the entire caliper of the absorbent article. Preferably, the acquisition region is positioned within the absorbent article such that the intended loading point is centered with respect to the acquisition region.
The absorbent article of the present invention comprises at least one waist region. The term xe2x80x9cwaist regionxe2x80x9d as used herein refers to those regions forward and/or backward of the above mentioned acquisition region of the absorbent article. Accordingly, the waist region may account for up to two thirds of the longitudinal dimension of the absorbent article. Like the acquisition region, the waist region extends over the entire transverse dimension of the absorbent article and extends over the entire caliper of the absorbent article. The waist regions are typically intended to be positioned in close proximity to the front waist region or the back waist region respectively of the wearer during use.
The absorbent article of the present invention comprises a first storage region and a second storage region. The term xe2x80x9cstorage regionxe2x80x9d as used herein refers to those regions of the article which are intended to ultimately store the urine. Typically, these regions exhibit a higher suction than for example the acquisition region of the article. Accordingly, the combination of all storage regions will contain most of the acquired liquid in the limit of long wearing times if the article is loaded with less than 75% of its total design capacity. Whilst first storage region and second storage region of the may be regions of one larger storage region, first storage region and second storage region of the article of the present invention are symmetrically different from each other.
The term xe2x80x9csymmetrically differentxe2x80x9d refers to a first storage region and a second storage region, both of these regions being comprised in another storage region. In this context, first storage region and second region are defined in the following way:
I. A storage region S having a total capacity of at least 20% of the total design capacity of the absorbent article is selected (this could for example be the front or the back waist region) which is connected in the x,y-dimension. Connected in the x,y-dimension means that in the x-y plane (2 dimensional) there exists a continuous curved line that connects the projections of any points A and Axe2x80x2 that are part of region S onto the x,y-plane without leaving the projection of region S onto the x,y-plane.
II. The above region S is divided into two sub regions S1 and S2 which satisfy the following requirements:
A. The storage capacity of S1 is substantially equal to the storage capacity of S2.
B. The storage capacity of S1 is more than 40% of the storage capacity of S.
C. Regions S1 and S2 are connected in the x,y-dimensions.
D. Both regions do not overlap in the z-direction.
E. Region S1 is closer to the acquisition region than region S2. In this context, the term xe2x80x9ccloserxe2x80x9d refers to the distance of the capacity centerpoint of region S1 being at least 3 cm closer to the loading point than the capacity centerpoint of region S2. The capacity center point is given by the center of gravity of the liquid stored in the region when the article is fully loaded via the capacity dunk test.
It is to be understood in this context that these regions are defined in a purely geometric way. In particular, there is no need that the positioning of these regions is reflected in the structure of the article such as by a change in material.
Optionally, the absorbent article according to the present invention may comprise a liquid handling member which is intended to transport urine from the acquisition region to a waist region and potentially to a storage member positioned inside a waist region.
The process for handling urine according to the present invention comprises a step of acquiring urine into the article of the present invention at the acquisition region of the article. Typically, the step is triggered by the disposal of urine onto the acquisition region of the article by the wearer. Preferably, the acquisition rate of the article during the step is sufficiently high to prohibit liquid runoff from the article which subsequently may lead to leakage and to minimize skin contact with the urine. During this acquisition step, a certain volume of urine is acquired into the article which is a fraction A of the total design capacity of the absorbent article.
The process of the present invention further comprises a step of storing a first portion of the acquired liquid in the first storage region and a second portion of the acquired liquid in the second storage region. The fraction of the acquired liquid which is stored in the first storage region is referred to as B1 whereas the fraction of the acquired liquid which is stored in the second storage region is referred to as B2. In the process of the present invention, fractions B1 and B2 are at least 10 percent, preferably at least 20 percent, more preferably at least 30 percent, most preferably at least 40 percent.
During the process of the present invention the ratio of B1/B2 for any value of fraction A between 20 percent and 80 percent differs by less than 30 percent from the ratio of B1/B2 for a fraction A of 20 percent, preferably differs by less than 20%, more preferably differs by less than 10%, most preferably differs by less than 5%. In other words, the ratio of the amount of liquid stored in the first liquid storage region to the amount of liquid stored in the second liquid storage region remains relatively constant over a wide range of different loadings of the absorbent article. Hence, the acquired liquid is distributed evenly between first storage region and second storage region such that the caliper increase over the storage region as a whole can be minimized and the material can be utilized most efficiently.
Optionally, the process of the present invention may comprise a step of transporting at least a portion of the acquired liquid from the acquisition region to the first storage region and/or to the second storage region. This process step may be carried out by the optional liquid handling member of the absorbent article of the present invention.
The absorbent article according to the present invention is capable of storing acquired liquid evenly in the first storage region and in the second storage region. This allows that the caliper increase or the storage region as a whole can be minimized and that the material of the storage regions can be utilized most efficiently. For the purpose of this invention, this capability is quantified by the fill ratio test defined hereinafter. The absorbent article according to the present invention has a fill ratio difference of less than 10 percent according to the fill ratio test disclosed herein, preferably of less than eight percent, more preferably of less than six percent, most preferably of less than four percent.
Optionally, the process for handling urine according to the present invention comprises a step of attaching the absorbent article to the lower torso of the wearer. During the step, the attachment of the article is achieved by means of the attachment means unitary with the article. The step may be carried out by the wearer himself or the step may be carried out by a caregiver. The purpose of the step is to align urethra with the acquisition region of the article.
In the following, a suitable embodiment of the liquid handling member will be described. The liquid handling member is assembled from an open celled foam material which is completely enveloped by a membrane. A suitable membrane material is available from SEFAR of Ruschlikon, Switzerland, under the designation SEFAR 03-20/14. A suitable foam material is available from Recticel of Brussels, Belgium, under the designation Bulpren S10 black. A suitable technique to completely envelope the foam material with the membrane material is to wrap the membrane material around the foam material and to subsequently heat seal all open edges of the membrane material. It will be readily apparent to the skilled practitioner to choose other similarly suitable materials. Depending on the specific intended application of the liquid handling member, it may also be required to choose similar materials with slightly different properties. After assembly, the liquid handling member is activated by immersing the liquid handling member in water or in synthetic urine until the liquid handling member is completely filled with liquid and until the membranes are completely wetted with liquid. After activation, a part of the liquid inside the liquid handling member may be squeezed out by applying an external pressure to the liquid handling member. If the activation of the liquid handling member was successful, the liquid handling member should not suck air.
The particular geometry of the liquid handling member of the present invention can be varied according to the specific requirements of the intended application. If, for example, the liquid handling member is intended to be used in an absorbent article the liquid handling member may be defined such that its zone of intended liquid acquisition fits between the legs of the wearer and further that its intended liquid discharge zone matches the form of the storage member associated to it. Accordingly, the outer dimensions of the liquid handling member such as length, width, or thickness may also be adapted to the specific needs of the intended application. In this context, it has to be understood , however, that the design of the outer form of the liquid handling member may have an impact on its performance. For example, the cross section of the liquid handling member directly impacts on its liquid flow rate.
For application of the liquid handling member in an absorbent article according to the present invention, the liquid handling member may be combined with a storage member. The term xe2x80x9cliquid storage memberxe2x80x9d refers to an article which is capable of acquiring, distributing and/or storing liquid. The volume of the liquid storage member may vary with the amount of stored liquid such as by swelling. Typically, the storage member will imbibe the liquid by means of capillary suction and/or osmotic pressure. Other storage members may also use vacuum as a means to store the liquid. The liquid storage member is further capable of holding at least a portion of the stored liquid under pressure. Suitable storage members are well known in the art and may comprise for example a super absorbent polymeric material such as polyacrylate. The storage member may further comprise a fibrous structure, such as a pad of cellulosic fibers, in which the particulate superabsorbent material is dispersed. A suitable absorbent gelling material is ASAP400 available from Chemdal Ltd., United Kingdom. Further examples of suitable superabsorbent polymers, often also referred to as xe2x80x9chydrogen forming polymerxe2x80x9d or xe2x80x9cabsorbent gelling materialxe2x80x9d, are described in U.S. Pat. No. 5,562,646 (Goldman et al.), issued Oct. 8, 1996 and U.S. Pat. No. 5,599,335 (Goldman et al.), issued Feb. 4, 1997.
In order to pick up the liquid discharged from the liquid handling member, the storage member may be placed in direct liquid communication with the intended liquid discharge zone of the liquid handling member.
Other liquid handling members suitable for the purposes of the present invention are described for example in the PCT patent application No. PCT/US98/13497 entitled xe2x80x9cLiquid transport member for high flux rates between two port regionsxe2x80x9d filed in the name of Ehrnsperger et al. filed on Jun. 29, 1998, and in the following PCT patent applications co-filed with the present application entitled xe2x80x9cHigh flux liquid transport members comprising two different permeability regionsxe2x80x9d (PandG case CM1840MQ) filed in the name of Ehrnsperger et al., xe2x80x9cLiquid transport member for high flux rates between two port regionsxe2x80x9d (PandG case CM1841MQ) filed in the name of Ehrnsperger et al., xe2x80x9cLiquid transport member for high flux rates against gravityxe2x80x9d (PandG case CM1842MQ) filed in the name of Ehrnsperger et al., xe2x80x9cLiquid transport member having high permeability bulk regions and high bubble point pressure port regionsxe2x80x9d (PandG case CM1843MQ) filed in the name of Ehrnsperger et al. All of these documents are enclosed herein by reference.
In one embodiment of the present invention, the liquid handling member of the present invention is geometrically saturated or substantially geometrically saturated with free liquid. The term xe2x80x9cfree liquidxe2x80x9d as used herein refers to liquid which is not bound to a specific surface or other entity. Free liquid can be distinguished from bound liquid by measuring the proton spin relaxation time T2 of the liquid molecules a according to NMR (nuclear magnetic resonance) spectroscopy methods well known in the art.